The prevalent mode of document preparation to date has been (1) a serial mode of manufacturing and (2) a dependency on data source availability that controls publishing schedules. The process also entails transferring client data from their preparation system, such as Word, to another manufacturing system for typesetting and preparation for print. In this process, the printer can introduce printer's errors (PEs, not billable to client), which must be separated from author's alterations (AAs, billable) during the billing process.
When a set of documents shares text or other elements, any changes to the elements must be rippled through the entire set of documents, which often have different publication dates. The prevalent manual solution is to distribute notes to the editors responsible for individual documents that require changes. This method does not guarantee currency (because of other changes that may occur during the elapsed time between publication dates) and does not enforce the change process itself.
Older electronic methods of approaching this problem, such as the boilerplate library, introduced on early proprietary word-processing systems, often imported the boilerplate element into the document itself. A later, more generalized method involved the use of Standard Generalized Markup Language (SGML), an ISO international standard. SGML sets out a standard, open method for writing a set of rules for marking up a group of documents sharing the same general structure and content types. SGML introduced a method for storing boilerplate or standing text and inserting it by reference; the boilerplate could reside outside the document itself. However, the reference was still embedded in the document stream and the document had to identify the source of the boilerplate reference. There was no efficient way to handle fragment publishing.
A later adaptation of SGML is Extensible Markup Language (XML), also a method of describing the structure and content elements of documents, it has won acceptance on the World Wide Web (WWW). XML, like SGML, effectively separates structure and content from visual formatting. The challenge posed to the inventors was to develop a mechanism that effectively incorporated shared elements without embedding them in a streaming document. The invention's use of XML solved the problem of enforcing structure and describing content, and a further separation—of structure from content—was realized by using XML elements to point to content without containing it. The result is a virtual document.